Aromatics endoperoxides

The power of fast reaction techniques for examining the details of reaction processes is illustrated by studies made on the photocycloreversion of an aromatic endoperoxide . Rupture of a single C-O band occurs in the reactive Sj (thc ) state within 0.35 ps of excitation. The generated biradical then decays with a lifetime of... 

Ultrafast techniques are finding increasing applications in elucidating the mechanisms of photoreactions. For example, this powerful technique has been applied to photochemical ring-opening of cyclo-octatriene (Reed et al.). and the photo-cycloreversion of an aromatic endoperoxide (Emsting et al.). In the latter case, a C-0 bond in the S3 state ruptures within 0.35 ps of excitation. 

Another ps kinetic study considers the mechanism of the photocycloreversion of aromatic endoperoxides. 91 steps which... 

Hydrogen abstraction from lipids by triplet states of benzophenone derivatives followed directly by the use of laser flash techniques allows the separation of physical quenching processes from chemical reactions of the excited state. 98 xhe production of 2 by the photochemical decomposition of aromatic endoperoxides has also been studied by ps kinetic procedures. 99 mechanistic study has also been reported on the phototransformation of 3-nitrophenol in aqueous solution. 99 There is a strong wavelength dependence of the low quantum yield for the phototransformation in this system. 

The mechanism is also consistent with the observation that cyclic diacyl hydrazines are far more chemiluminescent than similar acyclic compounds. The bicyclic peroxide intermediate shown in Scheme 6 may be precluded by rupture of one C-N bond after the addition of the hydrogen peroxide anion, but before the formation of an anti-aromatic endoperoxide that decomposes to form the emitter. Obtaining hard evidence for the existence of these... 

MoUenhauer D, Corral I, Gonzalez L (2010) Four plus four state degeneracies in the 0-0 photolysis of aromatic endoperoxides. J Phys Chem Lett 1 1036... 

Aliphatic Unsaturated Endoperoxides Aliphatic Saturated Endoperoxides Aromatic Endoperoxides... 

Reactive sy -h/s-epoxides available from the anthracene-endoperoxides by low-temperature irradiation at long wavelength could be thermally isomerized to benzocyclobutenic diethers and other products. A new kind of isomerization of aromatic endoperoxides, which is initiated by a Grob-fragmentation step, was described recently for anthracene and naphthalene bis-epoxides. The photochemistry of aromatic... 

Jesse, K., Markert, R., Comes, F.J., Schmidt, R., and Brauer, H.-D., Picosecond photochemistry the mechanism of photocycloreversion of aromatic endoperoxides, Chem. Phys. Lett., 166,95,1990. 

Jesse, K. and Comes, F.J., Rate parameters for the two-step photofragmentation of aromatic endoperoxides in solution, /. Phys. Chem., 95, 1311, 1991. 

Jesse, K.J., Structural impacts on the photodissociation dynamics of aromatic endoperoxides in solution, Chem. Phys. Lett., 264, 193,1997. 

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